The present invention relates to a measuring device and a method for locating objects enclosed in a medium using high-frequency electromagnetic signals in a frequency range between 1 and 5 GHz.
As a recent development, high-frequency electromagnetic signals are used in addition to inductive sensors—which have been known for a long time—to locate objects enclosed in a medium. Measuring devices of this type include, e.g., antennas for radiating high-frequency radar signals and microwaves.
Antennas for devices that are designed to detect objects such as lines or pipes in walls are generally optimized for transmitting and/or receiving high-frequency (HF) radar signals. An antenna of this type is known, e.g., from DE 10104863 A1.
The antenna described in DE 10104863 Al is a single-pieced, planar antenna, which is fixed in position with high mechanical stability on a printed circuit board and generates a relatively symmetrical radiation pattern with largely reduced minor lobes and/or sidelobes. The known antenna is composed of an electrically conductive plate, which includes two angled lateral sections on diametrically opposite edges, the angled lateral sections serving as conducting arms for coupling the antenna to a power supply network.
Locating devices with an antenna may be used in particularly diverse manners, since they are not limited to magnetic materials or the presence of a power supply network. Instead, they register a change in the dielectric constants of the material to be investigated, thereby making it possible to detect, e.g., plastic pipes, air inclusions, and cavities during a measurement.
Devices of this type have a disadvantage, however, namely that they are influenced by the structure of the wall, ceiling or floor, i.e., of the material surrounding the enclosed object. This influence may be relatively great, in some cases even greater than the influence of the enclosed object itself. With radar devices, it is therefore difficult to distinguish between wall structures and inhomogeneities of objects.